Unidirectional-driven drug infusion device

ABSTRACT

A unidirectional-driven drug infusion device, includes: a reservoir, a piston and a screw, the piston is arranged in the reservoir; a driving module which includes at least one driving wheel and at least one driving arm that cooperate with each other, the circumferential surface of the driving wheel is provided with wheel teeth; a power module coupled to the driving arm; a control module, connected to the power module, controls the power module to apply different driving powers to the driving arm, making the driving arm perform linear reciprocating motion; and a friction member which is in contact with the surface of the driving wheel. This device can fully utilize the internal space of the infusion device, and its weight and volume is reduced.

TECHNICAL FIELD

The present invention mainly relates to the field of medicalinstruments, in particular to a unidirectional-driven drug infusiondevice.

BACKGROUND

A drug infusion device can continuously deliver drug into a patient'sbody for disease treatment. Drug infusion devices are widely used in thefield of diabetes treatment, which continuously infuse required dosageof insulin into the patient's subcutaneous tissue, thereby simulatingthe secretion function of the pancreas to keep the blood glucose stable.The drug fluid is usually stored inside the infusion pump. The existingdrug infusion device, controlled by remote device, is usually attacheddirectly on the patient's skin through a medical adhesive tape.

U.S. Pat. No. 6,656,158 B2 discloses a medicine infusion device, whichuses a linearly movable pawl to push gear teeth, thereby realizingmedicine infusion. Among them, the infusion device is additionallyprovided with an anti-reverse fixed pawl to avoid reverse rotation ofthe driving wheel. Therefore, its internal structure is complicated withlower utilization of the internal space, making the infusion devicelarge and heavy.

Therefore, the prior art urgently needs a unidirectional-driven druginfusion device with higher internal space utilization, lighter weight,and smaller volume.

BRIEF SUMMARY OF THE INVENTION

The embodiment of the invention discloses a unidirectional-driven druginfusion device, which uses a friction member contacting the surface ofthe driving wheel to prevent the driving wheel from reversing, therebyfully utilizing the internal space of the infusion device, and reducingthe weight and volume of the infusion device.

The invention discloses a unidirectional-driven drug infusion device,including: a reservoir, a piston and a screw, the piston, connected withthe screw, is arranged in the reservoir; a driving module which includesat least one driving wheel and at least one driving arm that cooperatewith each other, the circumferential surface of the driving wheel isprovided with wheel teeth which can be pushed to rotate the drivingwheel, driving the screw forward; a power module coupled to the drivingarm; a control module, connected to the power module, controls the powermodule to apply different driving powers to the driving arm, making thedriving arm perform linear reciprocating motion, driving the drivingwheel to rotate; and a friction member which is in contact with thesurface of the driving wheel and increases the maximum static frictionforce received by the driving wheel.

According to one aspect of the present invention, the power applied bythe power module to the driving arm includes different linear directionsor different magnitudes.

According to one aspect of the present invention, the driving armincludes a variety of different motion amplitudes or a variety ofdifferent motion rates.

According to one aspect of the present invention, the power moduleincludes a first power unit and a second power unit respectivelyconnected to the driving arm, and by the action of the power module, thedriving arm is controlled to push the wheel teeth in its one motiondirection.

According to one aspect of the present invention, the first power unitincludes an electrically driven linear actuator or an electricallyheated linear actuator while the second power unit includes anelectrically driven linear actuator, an electrically heated linearactuator or an elastic member, and the control module controls thefrequency or the magnitude of the power exerted by the first power unitand the second power unit, in order to control the motion amplitude ormotion rate of the driving arm.

According to one aspect of the present invention, the first power unitis an advancing member while the second power unit is a reset member,during the operation, the advancing member applies power to the drivingarm to push the wheel teeth forward, while the reset member appliespower to the driving arm to make the driving arm reset.

According to one aspect of the present invention, the driving wheel is aratchet wheel, the wheel teeth are ratchet teeth, and the driving arm isa pawl which pushes the ratchet teeth to make the ratchet wheel rotateintermittently.

According to one aspect of the present invention, the driving armincludes two driving ends, arranged up and down, whose front ends arenot flush, and the two driving ends can alternately push the wheelteeth.

According to one aspect of the present invention, the friction memberhas elasticity, and the contact position of the friction member with thesurface of the driving wheel includes the tooth surface or the non-toothsurface of the driving wheel.

According to one aspect of the present invention, it further includes abase including the friction member, and the driving wheel is movablyassembled on the base where the friction member is located, andfrictionally fits with the friction member.

According to one aspect of the present invention, the friction member isarranged on the base, and the friction member is frictionally fittedwith the side surface of the driving wheel.

Compared with the prior art, the technical solution of the presentinvention has the following advantages:

In the unidirectional drive medicine infusion device disclosed in thepresent invention, a control module, connected to the power module,controls the power module to apply different driving powers to thedriving arm, making the driving arm perform linear reciprocating motionand driving the driving wheel to rotate. The driving arm with thelinearly reciprocating motion has a narrow operating space, which makesthe internal structure of the infusion device more compact and reducesthe volume of the infusion device. In addition, the infusion device alsoincludes a friction member which is in contact with the surface of thedriving wheel and increases the maximum static friction force receivedby the driving wheel. After the maximum static friction force receivedby the driving wheel increases, when the driving arm slides on the wheelteeth, the driving wheel does not rotate, which improves the accuracy ofdrug infusion, eliminates safety hazards, and enhances user experience.

Furthermore, the driving arm includes a variety of different motionamplitudes or a variety of different motion rates. The driving arm withmultiple operating modes makes the infusion device have a variety ofdifferent infusion modes, therefore, the body fluid level can beprecisely controlled, enhancing the user experience.

Furthermore, the first power unit includes an electrically driven linearactuator or an electrically heated linear actuator while the secondpower unit includes an electrically driven linear actuator, anelectrically heated linear actuator or an elastic member. The poweroutput by the linear actuator can be controlled by the current, thus,making the power, the motion amplitude or rate of the driving arm stableand controllable. In addition, the elastic member can reset the drivingarm automatically without consuming power, thereby reducing the powerconsumption of the infusion device.

Furthermore, the driving arm includes two driving ends, arranged up anddown, whose front ends are not flush, and the two driving ends canalternately push the wheel teeth. The front ends of the two driving endsare not flush, therefore, the next pushing action can be implementedafter the reset distance of the driving arm is less than one toothpitch, which further reduces the operating space of the driving arm,thus, saving space, and further reducing the size of the infusiondevice.

Furthermore, the friction member has elasticity, and the contactposition of the friction member with the surface of the driving wheelincludes the tooth surface and the non-tooth surface of the drivingwheel. The elastic friction member can better increase the maximumstatic friction force. At the same time, the weight of the elasticfriction member is much lighter, and its shape, volume, and positionsetting can be flexibly designed, which not only reduces the weight andvolume of the infusion device, but also improves the utilization rate ofthe internal space of the infusion device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic diagram of a unidirectional-driven drug infusiondevice according to an embodiment of the present invention;

FIG. 1 b -FIG. 1 c are top views of two drug infusion devices withmultiple infusion modes according to an embodiment of the presentinvention;

FIG. 2 a -FIG. 2 b are schematic diagrams of the internal structure ofthe infusion module according to an embodiment of the present invention,and FIG. 2 b is the side view of the driving module in FIG. 2 a;

FIG. 3 is a schematic diagram of multiple linear reciprocating motionamplitudes of the driving arm according to an embodiment of the presentinvention;

FIG. 4 a -FIG. 4 c are schematic diagrams where the friction member isin contact with the driving wheel in the embodiment of the presentinvention;

FIG. 5 a -FIG. 5 c are schematic diagrams s of a driving arm includingtwo driving ends according to another embodiment of the presentinvention, and FIG. 5 b and FIG. 5 c are side views of FIG. 5 a.

DETAILED DESCRIPTION

As mentioned above, the internal structure design of the drug infusiondevice in the prior art is complicated with lower utilization of theinternal space, making the infusion device large and heavy.

After research, it is found that the cause of the above-mentionedproblem is that a fixed pawl is additionally provided inside theinfusion device to prevent the reversal rotation of the driving wheel.

In order to solve this problem, the present invention discloses aunidirectional-driven drug infusion device, which uses a friction memberfrictionally fitted with the driving wheel to prevent the driving wheelfrom reversing, therefore, fully utilizing the internal space of theinfusion device and reducing the size of the infusion device.

Various exemplary embodiments of the present invention will now bedescribed in detail with reference to the drawings. The relativearrangement of the components and the steps, numerical expressions andnumerical values set forth in the embodiments are not to be construed aslimiting the scope of the invention.

In addition, it should be understood that, for ease of description, thedimensions of the various components shown in the figures are notnecessarily drawn in the actual scale relationship, for example, thethickness, width, length or distance of certain units may be exaggeratedrelative to other structures.

The following description of the exemplary embodiments is merelyillustrative, and is not intended to be in any way limiting theinvention and its application or use. The techniques, methods anddevices that are known to those of ordinary skill in the art may not bediscussed in detail, but such techniques, methods and devices should beconsidered as part of the specification.

It should be noted that similar reference numerals and letters indicatesimilar items in the following figures. Therefore, once an item isdefined or illustrated in a drawing, it will not be discussed further infollowing description of the drawings.

FIG. 1 a is a schematic diagram of a relationship among modules of aunidirectional-driven drug infusion device according to an embodiment ofthe present invention. FIG. 1 b and FIG. 1 c are top views of aunidirectional-driven drug infusion device according to two differentembodiments of the present invention, respectively.

As shown in FIG. 1 a, the control module issues at least an instructionto control the power module to output driving power to the drivingmodule to drive the screw forward, thereby making the infusion devicecomplete drug infusion. For ease of description, the power module, thedriving module and the screw are together replaced by infusion module inthe following.

Referring to FIG. 1 b and FIG. 1 c , the unidirectional-driven druginfusion device according to the embodiment of the present inventionincludes: an adhesive patch 100, a control module 101, an infusionmodule 102, and an infusion needle 103.

The control module 101 is used to control the driving power output bythe power module to control drug infusion. The control module 101 mayalso establish wireless communication with a remote device (not shown).In one embodiment of the present invention, the control module 101further includes a power supply (not shown).

The infusion module 102 includes various units for achieving themechanical function of drug infusion, which will be described in detailbelow in conjunction with different embodiments.

In the embodiment of the present invention, the control module 101 andthe infusion module 102 are designed separately and connected by awaterproof plug. The infusion module 102 can be discarded after a singleuse, while the control module 101 can be reused, as shown in FIG. 1 b .In other embodiments of the present invention, the infusion module 102and the control module 101, connected by a wire, are disposed inside thesame housing 10, and both parts will be discarded together after asingle use, as shown in FIG. 1 c.

The adhesive patch 100 is used to attach the infusion module 102 or thecontrol module 101, or both of them as a whole on the skin surface.

One end of the infusion needle 103 is connected to the outlet of theinfusion module 102, while the other end pierces the skin to infuse thedrug subcutaneously. In the embodiment of the present invention, theinfusion needle 103 is provided at one end of the infusion module 102.In other embodiments of the present invention, the infusion needle 103may also be disposed at other positions according to the functions orthe structural features of the device, such as being disposed at themiddle portion of the infusion device, which is not specifically limitedherein. The infusion needle 103 is a rigid infusion needle or a flexibleinfusion needle, or according to its different positions and functions,the infusion needle 103 can also adopt a combination of a rigid infusionneedle(s) and a flexible infusion needle(s), which is not specificallylimited herein. Preferably, in the embodiment of the present invention,the infusion needle 103 is a rigid infusion needle.

FIG. 2 a -FIG. 2 b are schematic diagrams of the internal structure ofthe infusion module 102 according to an embodiment of the presentinvention. FIG. 2 b is the side view of the driving module in FIG. 2 a.

For clearly showing the driving relationship of the driving modules, thepower modules are not shown in FIG. 2 b.

The internal structure of the infusion module 102 mainly includes areservoir 110, a piston 120, a screw 130, a driving module and a powermodule.

The reservoir 110 is used to store drugs which include, but are notlimited to, insulin, glucagon, antibiotics, nutrient solutions,analgesics, morphine, anticoagulants, gene therapy drugs, cardiovasculardrugs or chemotherapy drugs. Preferably, in this embodiment of thepresent invention, the drug is insulin.

The piston 120 is used to infuse liquid drug into the body.

The screw 130 is connected to the piston 120, thereby pushing the piston120 to advance, achieving the purpose of drug infusion. The screw 130 isa rigid screw or a flexible screw. When the screw 130 is a flexiblescrew, the screw 130 may be designed to be curved. In one embodiment ofthe invention, the flexible screw is formed by a plurality of threadedsub-units movably connected one by one.

The driving module, used to drive the screw 130 forward, includes atleast one driving wheel 140 and at least one driving arm 150 thatcooperate with each other. The driving wheel 140, the circumferentialsurface of which is provided with wheel teeth 141, is connected to thescrew 130.

Here, the cooperation means that when the driving arm 150 operates in acertain manner or mode, the driving wheel 140 will implement anassociated operating manner or mode to achieve the goal of driving thescrew 130 forward and completing the drug infusion.

It should to be noted here that the operating manner and operating modebelong to different technical concepts. The operating manner refers tothe specific working method or working form, such as unidirectionalreciprocating motion, of the driving arm 150. However, the operatingmode represents the effect, such as the change of the motion amplitudeor the motion rate, brought about by the operating manner of the drivingarm 150.

As in this embodiment of the present invention, the driving arm 150 canperform linear reciprocating motion in the L direction shown in FIG. 2 aand FIG. 2 b. Preferably, the driving arm 150 is a pawl while thedriving wheel 140 is a ratchet which can be more easily pushed,therefore, the wheel teeth 141 are ratchet teeth. As in anotherembodiment of the present invention, the driving wheel 140 is anordinary mechanical gear. Compared with the driving arm 150 operating ina rotary reciprocating motion, the linear reciprocating motion can saveits operating space, making the internal structure of the infusiondevice more compact, and reducing the volume of the infusion device.

Obviously, since the driving arm 150 is a driving structure while thedriving wheel 140 is a driven structure, the power module is coupledwith the driving arm 150 and outputs driving power to it. In this way,the driving arm 150 can perform linear reciprocating motion, and it willhave a variety of different operating modes as well, such as differentreciprocating motion amplitude or motion rate. The coupling methodbetween the power module and the driving arm 150 includes mechanicalconnection or electrical connection.

Preferably, in the embodiment of the present invention, the power moduleincludes a first power unit and a second power unit which areelectrically or mechanically connected to and apply driving power to thedriving arm 150, respectively. Preferably, in the embodiment of thepresent invention, the first power unit is an advancing member 180 whilethe second power unit is a reset member 170, as shown in FIG. 2 a. Theadvancing member 180 applies power to the driving arm 150, therebypushing the wheel teeth 141 to rotate the driving wheel 140, andrealizing drug infusion. The reset member 170 applies power to thedriving arm 150 which will reset and slide on the wheel teeth surfacewithout pushing the wheel teeth 141, therefore, the driving wheel 140does not rotate.

The reset member 170 includes an electrically driven linear actuator, anelectrically heated linear actuator, or an elastic member that canautomatically reset the driving arm 150 without using an external power.The type of elastic members includes, but is not limited to, at leastone compression spring, extension spring, torsion spring, elastic sheet,elastic plate, elastic rod, elastic rubber, and the like. Preferably, inthe embodiment of the present invention, the reset member 170 is atorsion spring which is more conducive to reset the driving arm 150.

In another embodiment of the present invention, the reset member 170 isan electrically driven linear actuator or an electrically heated linearactuator, such as a shape memory alloy. After being energized, thephysical form of the material of the linear actuator changes, whichmakes it shrinkage deformation, thereby outputting driving power. Thehigher the current is, the larger shrinkage deformation is, and thegreater the driving power outputs. Obviously, when the current isconstant, the driving power output by the linear actuator is constant.Therefore, the linear actuator can output a stable and controllabledriving power, which makes the infusion process stable and controllable,enhancing the user experience.

The advancing member 180, an electrically driven linear actuator or anelectrically heated linear actuator, directly applies driving power tothe driving arm 150. Preferably, in the embodiment of the presentinvention, the advancing member 180 is a shape memory alloy.

As shown in FIG. 2 a, the principle of the driving arm 150 driving thedriving wheel 140 to rotate in the embodiment of the present inventionis as follows. When the control module controls the advancing member 180to pull the driving arm 150 by force F_(P), the driving arm 150 advancesin L₁ direction, driving the driving end 151 to push the wheel teeth 141forward, thereby rotating the driving wheel 140, which makes the screw130 advance in the D_(A) direction and makes the infusion device performdrug infusion. At this time, the reset member 170 is an elastic memberwhich builds a gradually increasing elastic force F_(R). When theadvancing member 180 stops applying force and under the action of theelastic force F_(R), the driving arm 150 resets in L₂ direction. And thedriving end 151 stops pushing the wheel teeth 141, therefore the drivingwheel 140 stops rotating, and the screw 130 stops advancing, so that theinfusion device does not proceed drug infusion. The driving end 151 willslide on the surface of the wheel teeth 141 for reset until the drivingarm 150 stops motion. After these above two motions, the driving arm 150completes one linear reciprocating motion L.

By analogy, the driving arm 150 can complete multiple linearreciprocating motions. Obviously, when the infusion device of theembodiment of the present invention is in operation, the rotating mannerof the driving wheel 140 is intermittent rotation, that is, a manner ofrotation-stop-rotation-stop—. . . .

FIG. 3 is a schematic diagram of multiple linear reciprocating motionamplitudes of the driving arm 150 according to an embodiment of thepresent invention.

When the power received by the driving arm 150 is different, its motionrate or motion amplitude will be different. Therefore, the principle ofthe driving arm 150 implementing two linear reciprocating motionamplitudes according to the embodiment of the present invention is asfollows. The control module controls the power magnitude output by theadvancing member 180, while the reset member 170 implements resettingfunction, which makes the driving arm 150 perform linear reciprocatingmotion and makes the driving end 151 advance or reset. E_(n) representsthe position reached by the front end of the driving end 151, such asE₁, E₂, E₃, E₄, E₅. h_(n) represents the distance between two differentpositions E_(n). S_(n) represents the different positions of the point Sof the power output by the advancing member 180 during the linearreciprocating motion, and the dotted arc in FIG. 3 represents thetrajectory of S, therefore, S₁, S₂, S₃, S₄, S₅ corresponds with E₁, E₂,E₃, E₄, E₅, respectively. Obviously, the motion distance betweendifferent S_(n) can be used to represent the motion amplitude of thedriving arm 150. Preferably, in the embodiment of the present invention,h₁ is the pitch of wheel tooth, and h₁=3h₂. When the advancing member180, according to the instruction from the control module, makes thedriving end 151 to push the wheel teeth 141 from the E₁ to the E₂position, the advancing member 180 stops outputting power, and the resetmember 170 starts to work until resetting the driving end 151 to the E₃position, which makes the driving arm 150 complete the first linearreciprocating motion. The motion amplitude of the driving arm 150 isS₁-S₂ and S₂-S₃. During the first linear reciprocating motion, the frontend of the driving end 151 pushes a tooth forward by a distance h₁, thedrug infusion volume is V₁, and its reset distance is h₃. At this time,the infusion volume V₁ is regarded as the infusion increment in thisfirst infusion mode. When the next driving is performed, the advancingmember 180 outputs power. During the advancing distance h₃ of thedriving end 151, the driving wheel 140 does not rotate, nor does thedrug infusion perform. When the front end of the driving end 151 reachesthe E₂ position and continues to advance by a distance of h₄, the frontend of the driving end 151 pushes the wheel teeth 141 to the E₄position, the driving wheel 140 rotates, implementing the drug infusion.When the advancing member 180 stops outputting power, the reset member170 resets the driving end 151 to, such as, the E₅ position, therefore,the driving arm 150 completes the second linear reciprocating motion,and the driving arm 150 moves by S₃-S₄ and S₄-S₅. During the secondlinear reciprocating motion, the forward distance of the front end ofthe driving end 151 is (h₃+h₄), and the drug infusion volume is V₂. Atthis time, the infusion volume V₂ is the infusion increment in thissecond infusion mode. Obviously, the driving arm 150 only drives thedriving wheel 140 to rotate under the motion amplitudes S₁-S₂ and S₂-S₄in these two infusion modes. For the motion amplitude S₁-S₂ is greaterthan the motion amplitude S₂-S₄ (or h₁>h₄), V₁>V₂. Therefore, theinfusion device of the embodiment of the present invention has twodifferent infusion increments.

By analogy, the distance between E₁, E₂, E₃, E₄, E₅ can be arbitrarilyselected, such as h₁=h₂, h₁=2h₂, h₁=4h₂, etc., the infusion device has avariety of different infusion increments. Or the force point S can alsoreaches to the S₆ position, and S₄ and S₆ may not be the limit positionsfor the moving of the driving arm 150, which is not specifically limitedherein.

It should be noted that, as described above, in the embodiment of thepresent invention, the infusion device does not necessarily implementdrug infusion when the driving end 151 advances. Only when the drivingend 151 pushes the wheel teeth 141 forward, the infusion device does.

Each amplitude of the linear reciprocating motion of the driving arm 150corresponds with an infusion increment. Therefore, a variety ofdifferent motion amplitudes of the driving arm 150 make the druginfusion device have a variety of different infusion increments. Takinginsulin as an example, the infusion increment range of the drug infusiondevice in the embodiment of the present invention is 0.0005 U˜0.25 U(here, the infusion increment range includes endpoint values, that is,the infusion increment includes 0.0005 U and 0.25 U). In someembodiments of the present invention, the infusion increment of the druginfusion device may includes 0.001 U, 0.0025 U, 0.005 U, 0.0075 U, 0.01U, 0.025 U, 0.05 U, 0.075 U, 0.1 U, etc. Preferably, in the embodimentof the present invention, the infusion increment of the drug infusiondevice includes 0.005 U, 0.0075 U, 0.01 U, 0.025 U, and 0.05 U.

It should be noted here that when h₁=h₂, the infusion increment of theinfusion device always maintains V₁ with the motion amplitude of thedriving arm 150 always maintaining S₁-S₂ and S₂-S₁, which makes theinfusion relatively stable.

Another embodiment of the present invention can also increase thefrequency of the power output by the advancing member 180 to increasethe frequency of the linear reciprocating motion of the driving arm 150,thereby increasing the infusion rate. Therefore, the infusion devices inthe embodiments of the present invention can all change the powermagnitudes to make them have multiple infusion rates.

Here, the change of the power magnitudes can change the rate of theunidirectional motion, the rate of reciprocating motion, or thefrequency of reciprocating motion.

When the drug infusion device has multiple infusion modes, the user,according to the actual requirements, can flexibly select the infusionmode to stabilize the level of body fluid parameters. Taking insulinstabilizing blood glucose levels as an example, some users or bodytissues at the infusion site absorb insulin slowly. Users can choose ainfusion mode with smaller infusion increment or lower infusion rate,which not only stabilizes the blood glucose level, but also improves theutilization of insulin, reducing the burden on body tissues. As anotherexample, blood glucose spikes after a meal, so the user can first selectan infusion mode with a relatively large infusion increment or arelatively high infusion rate to suppress the rapid rise in bloodglucose, and then select an infusion mode with a medium infusionincrement or infusion rate, and finally, choose an infusion mode with arelatively small infusion increment or a relatively low infusion rate toslowly stabilize blood glucose at a reasonable level. For anotherexample, the bolus insulin required after each meal is different, andthe body's basal insulin requirement is also different at differentperiods of one day. Therefore, multiple infusion modes of the infusiondevice can be flexibly selected (by the user or automatically by theclosed-loop system) according to the actual requirements to achieve thegoal of precise control of blood glucose levels.

FIG. 4 a -FIG. 4 c are schematic diagrams where the friction member 191is in contact with the driving wheel 140 in the embodiment of thepresent invention.

The motion of the driving wheel 140 can directly drive the screw toadvance for drug infusion. Therefore, when the driving arm 150 does notpush the wheel teeth 141, the driving wheel 140 should stop rotating.Otherwise, there will be inaccurate drug infusion and safety risks.

Conventionally, the pawl should have a certain elasticity to ensure thatthe ratchet wheel can be continuously pushed. Therefore, in theembodiment of the present invention, when the driving end 151 slides onthe surface of the wheel teeth 141, the curved driving end 151 contactsthe wheel teeth 141 with exerting a certain pressure to the drivingwheel 140. Obviously, due to the structural characteristics of the wheelteeth 141 and the circumference of the driving wheel 140, the foresaidpressure applied by the driving end 151 is not equal at differentpositions. Therefore, when the driving end 151 slides (in the resetmotion, or just only slides forward without pushing the wheel teeth 141)on the surface of the wheel teeth 141, there is a possibility of forwardrotation or reverse rotation of the driving wheel 140. If such rotationsoccur, the accuracy of drug infusion will be reduced, bringing safetyrisks. Therefore, the embodiment of the present invention also includesa friction member 191, which is in contact with the surface of thedriving wheel 140 to increase the maximum static friction force receivedby the driving wheel 140 in order to ensure that when the driving arm150 slides on the teeth surface, the driving wheel 140 will not rotate,avoiding bringing security risks to users.

It should be noted that, compared with the aforementioned pushing forceexerted by the driving arm 150 to advance the wheel teeth 141, thispressure exerted by the curved driving arm 150 to the driving wheel 140is much smaller. Therefore, the existence of the friction member 191does not affect the actual pushing of the driving arm 150, that is, doesnot affect the drug infusion.

Other embodiments of the present invention do not limit the position ofthe friction fit, as long as the condition for increasing the maximumstatic friction force received by the driving wheel 140 can besatisfied. The embodiment of the present invention also does not limitthe material of the friction member 191, for example, the frictionmember 191 is an elastic component, a plastic component, or a metalcomponent. Preferably, the friction member 191 has elasticity, such assilica gel.

Here, the friction fit means that a certain pressure is preset betweenthe two structures to generate friction. The following friction fit hasthe same meaning as here.

Preferably, in the embodiment of the present invention, the contactposition of the friction member 191 with the surface of the drivingwheel 140 is located on the non-tooth surface of the driving wheel 140.As in an embodiment of the present invention, the infusion devicefurther includes a base 190 where the driving wheel 140 is movablyassembled. At this time, the friction member 191 is a part of the base190. In the embodiment of the present invention, the friction member 191is located at the position where the driving wheel 140 and the base 190are movably assembled, as shown in the dashed frame A in FIG. 4 a.

As shown in FIG. 4 b, in another embodiment of the present invention,the friction member 191 is disposed on the base 190. The position wherethe friction member 191 is frictionally fitted with the driving wheel140 is at position B or position C (the side surface of the drivingwheel 140, as shown by the dashed frame).

As shown in FIG. 4 c, the friction member 191 can also be in contactwith the tooth surface of the driving wheel 140, which can also increasethe maximum static friction force received by the driving wheel 140.

In an infusion device, a single pawl pushes the gear to rotate for thedrug infusion. However, conventional pawl pushing generally requires anadditional anti-reverse fixed pawl, or two opposed pawls to be used inconjunction to ensure that the gear does not rotate in the reversedirection. At this time, the number of pawls in the infusion device islarge, resulting in much more complicated design and lower spaceutilization rate.

In the infusion device disclosed in this present invention, there is noneed to additionally provide an anti-reversal pawl, but a frictionmember is used instead. And the friction member presses the surface ofthe driving wheel, increasing the maximum static friction force receivedby the driving wheel, which is different from the function of theanti-reversal pawl. At the same time, the volume, shape, and location ofthe friction member can be flexibly designed according to the internalspace of the infusion device, making full use of the internal space andeffectively reducing the volume of the infusion device. In addition,compared with the anti-reversal pawl, the weight of the friction memberis lighter, thus, reducing the weight of the infusion device andenhancing the user experience.

FIG. 5 a -FIG. 5 c are schematic diagrams s of a driving arm 250including two driving ends 251 a and 251 b according to anotherembodiment of the present invention. FIG. 5 b and FIG. 5 c are sideviews of FIG. 5 a.

It should be noted that, in order to clearly show the structuralrelationship between the driving arm 250 and the driving wheel 240, thepower module is not shown in FIG. 5 a -FIG. 5 c, which is similar to theaforementioned.

In another embodiment of the present invention, the driving arm 250includes two driving ends 251 a and 251 b which are arranged up anddown. The front ends of the two driving ends are not flush with adistance m, as shown in FIG. 5 b.

Here, the up and down arrangement means that when the driving arm 250 isviewed from its top, the driving end 251 a partially shields 251 b, asshown in FIG. 5 a. While the driving arm 250 is viewed from its side,the driving end 251 a and 251 b will be both shown, as shown in FIG. 5b.

Preferably, in the embodiment of the present invention, if the toothpitch is T, then m=T/n(n>1). Therefore, when the driving arm 250 isreset to a distance less than one tooth pitch T, the next pushing actioncan be started, which further reduces the motion space of the drivingarm 250. Preferably, m=T/2. At this time, the driving ends 251 a and 251b of the two driving arms can alternately push the wheel teeth 241. Eachtime when the driving arm 250 is reset by a distance of T/2, the nextpushing action can be started, as shown in FIG. 5 b and FIG. 5 c.

Obviously, the power module of the embodiment of the present inventioncan also apply different powers to the driving arm 250, making thedriving arm have a variety of different motion modes, as describedabove. Moreover, it is also possible to only use the driving end 251 aor 251 b to individually push the wheel teeth 241 to rotate the drivingwheel 240, advancing the screw 230.

In other embodiments of the present invention, m=(3T)/2, or the drivingarm may also include more than two driving ends which can alsoalternately push the wheel teeth. Or the infusion device includes morethan one driving arm, which is not specifically limited, as long as itcan meet the conditions for pushing the driving wheel to rotate.

In summary, the invention discloses a unidirectional-driven druginfusion device, which uses a friction member contacting the surface ofthe driving wheel to prevent the driving wheel from reversing, fullyutilizing the internal space of the infusion device, and reducing theweight and the volume of the infusion device.

While the invention has been described in detail with reference to thespecific embodiments of the present invention, it should be understoodthat it will be appreciated by those skilled in the art that the aboveembodiments may be modified without departing from the scope and spiritof the invention. The scope of the invention is defined by the appendedclaims.

1. A unidirectional-driven drug infusion device, includes: a reservoir,a piston and a screw, wherein the piston, connected with the screw, isarranged in the reservoir; a driving module which includes at least onedriving wheel and at least one driving arm that cooperate with eachother, a circumferential surface of the driving wheel is provided withwheel teeth which can be pushed to rotate the driving wheel, driving thescrew forward; a power module coupled to the at least one driving arm; acontrol module, connected to the power module, controls the power moduleto apply different driving powers to the driving arm, making the drivingarm perform linear reciprocating motion, thus, driving the driving wheelto rotate; and a friction member which is in contact with the surface ofthe driving wheel and increases the maximum static friction forcereceived by the driving wheel.
 2. The unidirectional-driven druginfusion device of claim 1, wherein the different driving powers appliedby the power module to the driving arm includes different lineardirections or different magnitudes.
 3. The unidirectional-driven druginfusion device of claim 2, wherein the driving arm includes a varietyof different motion amplitudes or a variety of different motion rates.4. The unidirectional-driven drug infusion device of claim 3, whereinthe power module includes a first power unit and a second power unitrespectively connected to the driving arm, and by the action of thepower module, the driving arm is controlled to push the wheel teeth inits only one motion direction.
 5. The unidirectional-driven druginfusion device of claim 4, wherein the first power unit includes anelectrically driven linear actuator or an electrically heated linearactuator while the second power unit includes an electrically drivenlinear actuator, an electrically heated linear actuator or an elasticmember, and the control module controls the frequency or the magnitudeof the power exerted by the first power unit and the second power unit,in order to control the motion amplitude or motion rate of the drivingarm.
 6. The unidirectional-driven drug infusion device of claim 5,wherein the first power unit is an advancing member while the secondpower unit is a reset member, during the operation, the advancing memberapplies power to the driving arm to push the wheel teeth forward, whilethe reset member applies power to the driving arm to make the drivingarm reset.
 7. The unidirectional-driven drug infusion device of claim 1,wherein the driving wheel is a ratchet wheel, the wheel teeth areratchet teeth, the driving arm is a pawl which pushes the ratchet teethto make the ratchet wheel rotate intermittently.
 8. Theunidirectional-driven drug infusion device of claim 1, wherein thedriving arm includes two driving ends, arranged up and down, whose frontends are not flush, and the two driving ends can alternately push thewheel teeth.
 9. The unidirectional-driven drug infusion device of claim1, wherein the friction member has elasticity, and the contact positionof the friction member with the surface of the driving wheel includesthe tooth surface or the non-tooth surface of the driving wheel.
 10. Theunidirectional-driven drug infusion device of claim 9, wherein theunidirectional-driven drug infusion device further includes a base whichincludes the friction member, and the driving wheel is movably assembledon the base where the friction member is located and frictionally fitswith the friction member.
 11. The unidirectional-driven drug infusiondevice of claim 10, wherein the friction member is arranged on the base,and the friction member is frictionally fitted with the side surface ofthe driving wheel.